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Allocating Memory from a NUMA Node

The following sample code demonstrates the use of the NUMA functions GetNumaHighestNodeNumber, GetNumaProcessorNode, and VirtualAllocExNuma. It also demonstrates the use of the QueryWorkingSetEx function to retrieve the NUMA node on which pages are allocated.


#define _WIN32_WINNT 0x0600

#include <windows.h>
#include <stdlib.h>
#include <stdio.h>
#include <psapi.h>
#include <tchar.h>

SIZE_T AllocationSize;
DWORD  PageSize;

void DumpNumaNodeInfo (PVOID Buffer, SIZE_T Size);

void __cdecl wmain (int argc, const wchar_t* argv[])
{
    ULONG HighestNodeNumber;
    ULONG NumberOfProcessors;
    PVOID* Buffers = NULL;

    if (argc > 1)
    {
        (void)swscanf_s (argv[1], L"%Ix", &AllocationSize);
    }

    if (AllocationSize == 0)
    {
        AllocationSize = 16*1024*1024;
    }

    //
    // Get the number of processors and system page size.
    //

    SYSTEM_INFO SystemInfo;
    GetSystemInfo (&SystemInfo);
    NumberOfProcessors = SystemInfo.dwNumberOfProcessors;
    PageSize = SystemInfo.dwPageSize;

    //
    // Get the highest node number.
    //

    if (!GetNumaHighestNodeNumber (&HighestNodeNumber))
    {
        _tprintf (_T("GetNumaHighestNodeNumber failed: %d\n"), GetLastError());
        goto Exit;
    }

    if (HighestNodeNumber == 0)
    {
        _putts (_T("Not a NUMA system - exiting"));
        goto Exit;
    }

    //
    // Allocate array of pointers to memory blocks.
    //

    Buffers = (PVOID*) malloc (sizeof(PVOID)*NumberOfProcessors);

    if (Buffers == NULL)
    {
        _putts (_T("Allocating array of buffers failed"));
        goto Exit;
    }

    ZeroMemory (Buffers, sizeof(PVOID)*NumberOfProcessors);

    //
    // For each processor, get its associated NUMA node and allocate some memory from it.
    //

    for (UCHAR i = 0; i < NumberOfProcessors; i++)
    {
        UCHAR NodeNumber;

        if (!GetNumaProcessorNode (i, &NodeNumber))
        {
            _tprintf (_T("GetNumaProcessorNode failed: %d\n"), GetLastError());
            goto Exit;
        }

        _tprintf (_T("CPU %u: node %u\n"), (ULONG)i, NodeNumber);

        PCHAR Buffer = (PCHAR)VirtualAllocExNuma(
            GetCurrentProcess(),
            NULL,
            AllocationSize,
            MEM_RESERVE | MEM_COMMIT,
            PAGE_READWRITE,
            NodeNumber
        );

        if (Buffer == NULL)
        {
            _tprintf (_T("VirtualAllocExNuma failed: %d, node %u\n"), GetLastError(), NodeNumber);
            goto Exit;
        }

        PCHAR BufferEnd = Buffer + AllocationSize - 1;
        SIZE_T NumPages = ((SIZE_T)BufferEnd)/PageSize - ((SIZE_T)Buffer)/PageSize + 1;

        _putts (_T("Allocated virtual memory:"));
        _tprintf (_T("%p - %p (%6Iu pages), preferred node %u\n"), Buffer, BufferEnd, NumPages, NodeNumber);

        Buffers[i] = Buffer;

        //
        // At this point, virtual pages are allocated but no valid physical
        // pages are associated with them yet.
        //
        // The FillMemory call below will touch every page in the buffer, faulting
        // them into our working set. When this happens physical pages will be allocated
        // from the preferred node we specified in VirtualAllocExNuma, or any node
        // if the preferred one is out of pages.
        //

        FillMemory (Buffer, AllocationSize, 'x');

        //
        // Check the actual node number for the physical pages that are still valid
        // (if system is low on physical memory, some pages could have been trimmed already).
        //

        DumpNumaNodeInfo (Buffer, AllocationSize);

        _putts(_T(""));
    }

Exit:
    if (Buffers != NULL)
    {
        for (UINT i = 0; i < NumberOfProcessors; i++)
        {
            if (Buffers[i] != NULL)
            {
                VirtualFree (Buffers[i], 0, MEM_RELEASE);
            }
        }

        free (Buffers);
    }
}

void DumpRegion (PVOID StartPtr, PVOID EndPtr, BOOL Valid, DWORD Node)
{
    DWORD_PTR StartPage = ((DWORD_PTR)StartPtr)/PageSize;
    DWORD_PTR EndPage   = ((DWORD_PTR)EndPtr)/PageSize;
    DWORD_PTR NumPages  = (EndPage - StartPage) + 1;

    if (!Valid)
    {
        _tprintf (_T("%p - %p (%6Iu pages): no valid pages\n"), StartPtr, EndPtr, NumPages);
    }
    else
    {
        _tprintf (_T("%p - %p (%6Iu pages): node %u\n"), StartPtr, EndPtr, NumPages, Node);
    }
}

void DumpNumaNodeInfo (PVOID Buffer, SIZE_T Size)
{
    DWORD_PTR StartPage = ((DWORD_PTR)Buffer)/PageSize;
    DWORD_PTR EndPage   = ((DWORD_PTR)Buffer + Size - 1)/PageSize;
    DWORD_PTR NumPages  = (EndPage - StartPage) + 1;

    PCHAR StartPtr = (PCHAR)(PageSize*StartPage);

    _putts (_T("Checking NUMA node:"));

    PPSAPI_WORKING_SET_EX_INFORMATION WsInfo = (PPSAPI_WORKING_SET_EX_INFORMATION)
        malloc (NumPages*sizeof(PSAPI_WORKING_SET_EX_INFORMATION));

    if (WsInfo == NULL)
    {
        _putts (_T("Could not allocate array of PSAPI_WORKING_SET_EX_INFORMATION structures"));
        return;
    }

    for (DWORD_PTR i = 0; i < NumPages; i++)
    {
        WsInfo[i].VirtualAddress = StartPtr + i*PageSize;
    }

    BOOL bResult = QueryWorkingSetEx(
        GetCurrentProcess(),
        WsInfo,
        (DWORD)NumPages*sizeof(PSAPI_WORKING_SET_EX_INFORMATION)
    );

    if (!bResult)
    {
        _tprintf (_T("QueryWorkingSetEx failed: %d\n"), GetLastError());
        free (WsInfo);
        return;
    }

    PCHAR RegionStart   = NULL;
    BOOL  RegionIsValid = false;
    DWORD RegionNode    = 0;

    for (DWORD_PTR i = 0; i < NumPages; i++)
    {
        PCHAR Address = (PCHAR)WsInfo[i].VirtualAddress;
        BOOL  IsValid = WsInfo[i].VirtualAttributes.Valid;
        DWORD Node    = WsInfo[i].VirtualAttributes.Node;

        if (i == 0)
        {
            RegionStart   = Address;
            RegionIsValid = IsValid;
            RegionNode    = Node;
        }

        if (IsValid != RegionIsValid || Node != RegionNode)
        {
            DumpRegion (RegionStart, Address - 1, RegionIsValid, RegionNode);

            RegionStart   = Address;
            RegionIsValid = IsValid;
            RegionNode    = Node;
        }

        if (i == (NumPages - 1))
        {
            DumpRegion (RegionStart, Address + PageSize - 1, IsValid, Node);
        }
    }

    free (WsInfo);
}


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